The majority of blunt chest injuries are minor contusions or abrasions; however, life-threatening injuries, including tension pneumothorax, hemothorax, and aortic rupture can occur and must be recognized early. This review focuses on the diagnosis, management, and disposition of patients with blunt injuries to the ribs and lung. Utilization of decision rules for chest x-ray and computed tomography are discussed, along with the emerging role of bedside lung ultrasonography. Management controversies presented include the limitations of needle thoracostomy using standard needle, chest tube placement, and chest tube size. Finally, a discussion is provided related to airway and ventilation management to assist in the timing and type of interventions needed to maintain oxygenation.

Introduction

Points & Pearls

Endotracheal tube (ETT) depth is measured based on the patient’s front teeth rather than the molars.

Larger tidal volumes may be temporarily required for patients with severe metabolic acidosis.

Why and When to Use, and Next Steps H4

Why to Use

Placing the ETT too deep may cause right mainstem intubation, hypoxemia, and pneumothorax. However, placing the ETT too shallow may risk injury to the vocal cords and accidental extubation. Standard approaches to verify ETT depth (eg, bilateral auscultation) are insensitive. Use of lower tidal volumes appears to prevent the development of acute respiratory distress syndrome, even in patients who do not have lung injury.

ETT position should still be verified with a chest radiograph for patients who will remain intubated for an extended period of time.

For tidal volume, 6 to 8 mL/kg ideal body weight is generally a safe initial setting, but further ventilator adjustment may be required, depending on the adequacy of ventilation and airway pressures.

Formula

Chula formula: ETT depth = 0.1 * [height (cm)] + 4

Additional Formulas

IBW, men = 50 kg + 2.3 * [height (in) - 60]

IBW, women = 45.5 kg + 2.3 * [height (in) - 60]

Usual tidal volume target = 6-8 mL/kg IBW

Calculator Review Author

Joshua Farkas, MD

Department of Primary Care

Clinical Assistant Professor

Department of Critical Care Medicine

Larner College of Medicine

University of Vermont, Burlington, VT

Critical Actions

Obtain chest radiograph and measurement of CO2 level (eg, end-tidal CO2 or blood gas analysis) to confirm ETT position and adequacy of ventilation.

Evidence Appraisal

The Chula formula was developed and validated by Techanivate et al (2005) at King Chulalongkorn Memorial Hospital in Thailand. The authors prospectively validated the use of this formula among 100 patients in Thailand. Patients were intubated and the ETT placed according to the formula. Subsequently, a bronchoscope was used to determine the relationship among the ETT, carina, and vocal cords. The distance between the ETT and carina ranged between 1.9-7.5 cm. No patient was at immediate risk of endobronchial intubation. The upper border of the ETT cuff was always > 1.9 cm below the vocal cords, avoiding risk of laryngeal trauma or inadvertent extubation.

Pak et al in 2010 and Hunyady et al in 2008 developed similar assessments of optimal ETT placement. The average of the 3 scores (Pak, Hunyady, and Chula) is nearly identical to the Chula formula.

Primary blast lung injury (BLI) is radiological and clinical evidence of acute lung injury occurring after blast injury that is not due to secondary or tertiary blast injury. The pathophysiology is thought to be due to capillary rupture within alveoli leading to hemorrhage and pulmonary edema, which then reduces gas exchange, causing hypoxia and hypercarbia.

Clinical suspicion of primary BLI should be high after blast injury within an enclosed space, as the blast wave becomes amplified as it reflects off of the structural walls (Leibovici 1996).

In the studies, patients diagnosed with BLI were intubated immediately or within 2 hours of presentation due to respiratory decompensation. Thus, patients breathing spontaneously and adequately 2 hours after injury are unlikely to require mechanical ventilation because of BLI alone (Pizov 1999, Avidan 2005).

Use the BLI Severity Score in patients who have sustained blast injury and have respiratory symptoms (eg, cough, cyanosis, dyspnea, hemoptysis).

Next Steps

Screening chest x-rays for asymptomatic patients are not recommended (Zara 2015), as patients with BLI present either immediately or early with hypoxemia. Contrary to previous belief that the clinical picture of BLI may develop over 24 to 48 hours, studies have shown that patients do not present with a delay in manifestation of lung injury (Pizov 1999, Avidan 2005).

Similarly, it was previously suggested that tympanic membrane rupture, the most common primary blast injury, was a marker for increased risk of development of BLI. Studies have shown that tympanic membrane perforation is in fact poorly correlated with BLI (Leibovici 1999, Ballivet de Regloix 2017).

Low inspiratory pressure with avoidance of positive end-expiratory pressure (PEEP) is ideal in BLI in order to avoid secondary barotrauma, arterial air embolism, or pneumothorax. However, patients with blast lung often have injury patterns similar to ARDS and require positive pressure ventilation and PEEP.

Other treatment considerations include avoiding aggressive intravenous hydration after physiology capture, as it can worsen pulmonary edema, and considering the need for a prophylactic thoracostomy tube before air transportation.

Calculator Review Author

Jennie Kim, MD

Department of Surgery

Maimonides Medical Center, Brooklyn, NY

Travis Polk, MD

Commander, Medical Corps, U.S. Navy

Los Angeles County+USC Medical Center

Los Angeles, CA

Evidence Appraisal

The original BLI Severity Score was proposed in 1999 by Pizov et al. The study evaluated 15 patients with primary BLI after explosions on 2 civilian buses. BLI Severity scores were compared to Murray scores for acute lung injury at 6 and 24 hours after injury; at 24 hours, there was good correlation between the proposed BLI score and the modified Murray score.

Three of the 3 patients (100%) with severe BLI who were still alive after 24 hours (1 patient died within 24 hours from intrapulmonary hemorrhage after being placed on extracorporeal membrane oxygenation) and 2 of 6 patients (33%) with moderate BLI developed acute respiratory distress syndrome (ARDS) (Murray score > 2.5). None of the 5 patients with mild BLI developed ARDS. Other unconventional respiratory therapies such as independent lung ventilation, high-frequency jet ventilation, and nitric oxide were used in patients with severe BLI with improvements in their PaO2 levels. When comparing mortality rates, 4 patients with severe BLI died, all 6 patients with moderate BLI survived, and 1 of the 5 patients with mild BLI subsequently died from a traumatic head injury.

One year after the study by Pizov et al, Hirshberg et al conducted a follow-up study of the 11 surviving original patients. None of the 11 survivors had pulmonary-related complaints, and lung physical examinations were normal with complete resolution of chest radiograph findings.

In comparison, Avidan et al, in 2005, evaluated 29 patients with primary BLI, and only 1 patient had died (death occurred 24 days after admission from sepsis and multiple organ failure). The authors concluded that death because of BLI in patients who survived the explosion is unusual. Although these 29 patients were not categorized by BLI severity scores, there were 7 patients with PaO2 / FiO2 ratios < 60, 4 patients requiring positive end-expiratory pressure (PEEP) > 10 cm H2O, and 3 patients requiring unconventional therapies such as high-frequency ventilation or nitric oxide inhalations. The decreased mortality rate compared to Pizov et al, despite the presence of patients with characteristics of severe BLI, may be attributed to improvements in critical care and respiratory management.

The study also assessed long-term outcomes by contacting 21 of 28 survivors (75%) from 6 months to 21 years after discharge. Sixteen patients (76%) were free of respiratory symptoms and did not require respiratory therapy. Five patients (24%) reported respiratory symptoms but 2 of the 5 had a past medical history of asthma and another 2 of the 5 were contacted less than 1 year after injury.

Describe different methods of thoracic decompression of pneumothorax and hemothorax and select patients who require admission.

Physician CME Information

Date of Original Release: June 1, 2016. Date of most recent review: May 10, 2016. Termination date: June 1, 2019.

Accreditation: EB Medicine is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians. This activity has been planned and implemented in accordance with the Essential Areas and Policies of the ACCME.

Credit Designation: EB Medicine designates this enduring material for a maximum of 4 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

ACEP Accreditation: Emergency Medicine Practice is approved by the American College of Emergency Physicians for 48 hours of ACEP Category I credit per annual subscription.

AAFP Accreditation: This Medical Journal activity, Emergency Medicine Practice, has been reviewed and is acceptable for up to 48 Prescribed credits by the American Academy of Family Physicians per year. AAFP accreditation begins July 1, 2015. Term of approval is for one year from this date. Each issue is approved for 4 Prescribed credits. Credit may be claimed for one year from the date of each issue. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

AOA Accreditation: Emergency Medicine Practice is eligible for up to 48 American Osteopathic Association Category 2-A or 2-B credit hours per year.

ABIM Accreditation: Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 4 MOC points in the American Board of Internal Medicine’s (ABIM) Maintenance of Certification (MOC) program. Participants will earn MOC points equivalent to the amount of CME credits claimed for the activity. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.

Specialty CME: Included as part of the 4 credits, this CME activity is eligible for 4 Trauma CME credits, subject to your state and institutional approval.

Needs Assessment: The need for this educational activity was determined by a survey of medical staff, including the editorial board of this publication; review of morbidity and mortality data from the CDC, AHA, NCHS, and ACEP; and evaluation of prior activities for emergency physicians.

Goals: Upon completion of this activity, you should be able to: (1) demonstrate medical decision-making based on the strongest clinical evidence; (2) cost-effectively diagnose and treat the most critical presentations; and (3) describe the most common medicolegal pitfalls for each topic covered.

Objectives: Upon completion of this article, you should be able to: (1) summarize the work-up, disposition, and immediate treatment of blunt thoracic trauma patients; (2) assess the benefits and pitfalls of different imaging modalities; and (3) describe different methods of thoracic decompression of pneumothorax and hemothorax and select patients who require admission.

Discussion of Investigational Information: As part of the journal, faculty may be presenting investigational information about pharmaceutical products that is outside Food and Drug Administration–approved labeling. Information presented as part of this activity is intended solely as continuing medical education and is not intended to promote off-label use of any pharmaceutical product.

Faculty Disclosure: It is the policy of EB Medicine to ensure objectivity, balance, independence, transparency, and scientific rigor in all CME-sponsored educational activities. All faculty participating in the planning or implementation of a sponsored activity are expected to disclose to the audience any relevant financial relationships and to assist in resolving any conflict of interest that may arise from the relationship. In compliance with all ACCME Essentials, Standards, and Guidelines, all faculty for this CME activity were asked to complete a full disclosure statement. The information received is as follows: Dr. Morley, Dr. Johnson, Dr. Leibner, Dr. Shahid, Dr. Parekh, Dr. Tainter, Dr. Jagoda, Dr. Shah, Dr. Damilini, Dr. Toscano, and their related parties report no significant financial interest or other relationship with the manufacturer(s) of any commercial product(s) discussed in this educational presentation.

Commercial Support: This issue of Emergency Medicine Practice did not receive any commercial support.

Earning Credit: Two Convenient Methods: (1) Go online to www.ebmedicine.net/CME and click on the title of the article. (2) Mail or fax the CME Answer And Evaluation Form (included with your June and December issues) to EB Medicine.

Hardware/Software Requirements: You will need a Macintosh or PC to access the online archived articles and CME testing.

Additional Policies: For additional policies, including our statement of conflict of interest, source of funding, statement of informed consent, and statement of human and animal rights, visit www.ebmedicine.net/policies.